Electric switch



Oct. 7, 1958 H. J. CROMWELL ,8

- ELECTRIC SWITCH Filed Aug. 26, 1955 v 6 Sheets-Sheet 1 Fig.

. INVENTIOR. Hora/d J Cromwell H/s Attorney I Oct. 7, 1958 J, CROMWELL 2,855,475

ELECTRIC SWITCH Fi Ied Aug. 26, 1955 6 Sheets-Sheet 2 Fig. 2

INVENTOR. Harold J, Cromwell Fig.4 BY

is A ffomey Oct. 7, 1958 H. J.'CROMWELL 7 2,855,475

ELECTRIC SWITCH Filed Aug. 26, 1955 I e Sheets-Shea; s

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ELECTRIC SWITCH Oct. 7, 1958 6 Sheets-Sheet 4 Filed Aug. 26, 1955 v 2.; 54 8 46 I43 I58 44 7 E 60 70 7 148 I68 :56

I L0 I60 is Attorney Oct. 7, 1958 Filed Aug. 26, 1955 H. J. CROMWELL ELECTRIC SWITCH 6 Sheets-Sheet 5 INVENTOR.

Harold J. Cromwell is Afro/05y 1958 H. J. CROMWELL 2,855,475

ELECTRIC SWITCH Filed Aug. 26, 1955 6 Sheets-Sheet 6 INI "EQ fOR. B fiaro/a' J. Cromwell is Attorney Fig. ,/7

United States Patent Ofitice Patented Oct. 7, 1958 ELECTRIC SWITCH Harold J. Cromwell, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 26, 1955, Serial No. 530,801

8 Claims. (Cl. 200-34) This invention relates to electric switches and more particularly to a switch which controls the energization of the starting motor for an internal combustion engine.

The present invention, in its broader concepts, is directed to a switch for the starting motor circuit of an internal combustion engine which switch incorporates a time delay and lockout mechanism which will prevent re-energization of the starting motor circuit until a lapse of time has occurred.

The switch, according to the present invention, will, through its snap acting contacts, close and open the starting motor circuit whenever the switch is actuated and a sufiicient time delay occurs between the successive attempts to actuate the contacts. Thus, the switch, when installed in the circuits which directly or indirectly energize a starting motor, will prevent rapid successive intermittent starter energization which is detrimental to not only the starting motor but also to the starter drive mechanism and the gears associated therewith.

It is an object, therefore, of the present invention to provide a starter switch with a self-contained time delay mechanism which will prevent rapid re-energization of the starting motor.

Another object of the present invention is to control the movement of a movable contact in a reciprocal plunger type switch with a restraining means which is freely movable in one direction and has a restrained movement in the opposite direction and a means for temporarily preventing the movement of the plunger after the plunger has been moved to and from a predetermined position.

A further object of the present invention is to include a fluid dashpot in a plunger operated electric switch and to include lockout means in said switch, which lockout and dashpot cooperate with each other to prevent movement of the plunger for a time interval after the plunger has caused a movable contact to be moved sequentially to a circuit closing and opening position.

Still another object of the present invention is to provide a plunger operated starter switch with a fluid dashpot and a plurality of locking means so that the freedom of movement of the plunger will be delayed for a time interval after the plunger has been moved to cause a snap acting toggle actuated contact to move respectively to a circuit closing and opening position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figure 1 is an exploded view showing, in perspective, various parts of the switch according to the present invention.

Figures 2, 3 and 4 show the parts of the switch according to the present invention at rest wherein:

Figure 2 is a top view of the switch showing certain components of the switch in section;

Figure 3 is a side view in section showing the various components of the switch; and,

Figure 4 is a bottom plan view of a portion of the switch in Figures 2 and 3.

Figure 5 is a view of the switch in Figure 3 showing the location of the switch parts when the switch plunger is slightly depressed.

Figure 6 is an enlarged sectional top view of a portion of the switch showing the location of the contacts when the parts of the switch are moved to the position shown in Figure 5.

Figure 7 is a View of the switch in Figure 3 showing the location of the switch parts with the plunger almost fully depressed and the switch contacts in the open circuit position.

Figure 8 is an enlarged sectional top view of a portion of the switch showing the loctaion of the contacts when the parts of the switch are moved to the position shown in Figure 7. I

Figure 9 is a view of the switch in Figure 3 showing the location of the switch parts with the plunger in the fully depressed position and the contacts in the closed circuit position.

Figure 10 is an enlarged sectional view of a portion of the switch showing the contacts when the parts of the switch are moved to the position shown in Figure 9.

Figure 11 is a view of the switch in Figure 3 showing the location of the switch parts after the plunger is moved from the position shown in Figure 9 and is in the position shown in Figure 7 and showing the contacts in the closed circuit position.

Figure 12 is an enlarged sectional view of a portion of the switch showing the contacts when the parts of the switch are moved to the position shown in Figure 11.

Figures 13-17 show a modification of the switch according to the present invention wherein:

Figure 13 is a top plan view of the modified form of the switch shown in the preceding views;

Figure 14 is a side plan view of the switch in Figure 13;

Figure 15 is a sectional view along line 1515 in Figure 14;

Figure 16 is a sectional view along line 1616 in Figure 13 showing the parts of the switch in the at rest position; and,

Figure 17 is a sectional view along line 1616 in Figure 13 showing the parts of the switch when the contacts are in the circuit closing position when the plunger has been initially fully depressed.

In the drawings, the numeral 20 designates a U-shaped channel member which carries the various components of the switch which include: a contact support 22, a reciprocatable means which includes the plunger 26 and a U-shaped channel member or carriage 28, a means which will prevent movement of the carriage 25 under certain conditions which means includes members 30 and 32 shown in Figure l, and a restraining means which includes member 34 and the fluid dashpot 36. shown in Figure 2.

The contact support 22 has a base 38 which is formed of insulating material and is immovably secured to the arms 40 and 42 of the channel member 20 by lugs 44 and 46. Support 22 carries a stationary contact 48 which is electrically connected with terminal 59 and a toggle actuated movable contact 52 which is electrically connected with terminal 54. The toggle means for moving contact 52 includes a U-shaped channel member 56 immovably mounted on support 22 and electrically connected with terminal 54 by one of its arms 58 by means of rivet 60. The channelmember 56 has the ends of its arms 58 and 62 notched to provide a pivot support for the bifurcated end of the member 64 which carries the contact 52, and is also provided with an elongated opening 66 and a pair of upturned lugs 68 on each end. The lugs 68 serve to strengthen the mid-portion of the channel member 56 whereon the member 70, which is preferably formed of insulating material, is slidably mounted. The member 70 has one extending edge engaging member 38 and is held in surface to surface contact with the midportion of channel member 56 by a spring 72. This spring is held under tension and has one end anchored to member 70 and the other end connected to the midportion of the bifurcated member 64. The loop of the spring 72, connected with the member 70, is preferably sized to be received in opening 66 and engage the side walls thereof to aid in the positioning of member 70 on member 38. Member 38 also provides a support for a stop member 74. This member 74 is preferably secured to member 38 by riveting and has an insulated outer surface spaced from the stationary contact 48.

From the above arrangement of parts, it is apparent that, as the member 70 is moved relative to members 38 and 56, the spring 72 will cause the bifurcated member 64 to move with a snap action between the stop member 74 and the stationary contact 48. The snap action movement of the contacts 48 occurs through the toggle action of the parts which are arranged. so member 70 will have a considerable range of movement before the toggle actron occurs.

The carriage 28 is sized to be moved between the arms 40 and 42 of channel member and has curved lugs 76 formed on each of its arms 78 and 80. The curved lugs 76 are arranged to slide upon the surface of member 38 as the member 28 is reciprocated between the arms 48 and 42 of member 20. The carriage 28 is also provided with a suitably located and sized slot 82 which will receive the annular groove 84 on plunger member 26 to couple the plunger 26 and carriage 28 together so that the axial movement of the plunger 26 will be imparted to the carriage 28. The member 28 has an elongated slot 86, the purpose of which will be hereinafter apparent, extending a considerable distance in the bottom wall 88 and the arm 78. Included also in wall 88 of carriage 28 is an opening 90, the purpose of which will also be hereinafter described.

The member 20 is provided with a plurality of openings 92, 96, 98, 100, 102 and 104 which are located and sized substantially as shown in the drawing, the purpose of which will be hereinafter described. Included also in the bottom wall 106 of channel member 20 is a pair of bent portions 108 which are struck out from the material of wall 106 to form guides for member 34. Attached to the bottom wall 106 of member 2! are channel members 110 and 112. These channels 110 and 112 are located as shown in Figure 3 to provide a hinge for members and 32 which are most clearly shown in Figure l.

The member 34 is preferably formed of stamped metal as shown in Figure 1 to have an upwardly extending T- shaped lug 114 which is received in opening 98. The member 34 also is provided with an enlarged centrally located opening 116 and a pair of spaced downwardly bent lugs 120 which are formed in the member 34 as shown in Figure 1 adjacent opening 116. A lug 122 is provided by the edge of an inclined downwardly, partly struck out portion of member 34 in the position shown in the drawing.

The member 30 is provided with a pair of upstanding lugs 124 and 126 which are integrally formed with the part and located as shown in Figure 1. Member 30 also has lugs 128 which are located to be hingedly received in the channel member 110. The member 30, when located in channel member 110, will be constantly urged toward member 20 by spring 130 which has one end anchored on the lug 132 and the other end resting on the wall 106 of member 20.

The member 32 has a bent surface 134 formed as shown in Figures 1 and 2 and has an upwardly bent lug be upwardly urged toward member 20 by spring 142. If

desired, a cover 139 may be secured to the channel member 20 to conceal the members 30 and 32.

The fluid dashpot 36, which is most clearly shown in Figures 2 and 3, has a cover 143 held in position by a conventional snap yoke 144 which is received in notches 146 in arm 42 of member 20. The base 148 of the dashpot is held in position on arm 42 by means of rivets 150 which extend through openings 104. The dashpot 36 is provided with a plunger 152 which has one end connected with lug 114 and its other end extending through opening and sealed by the O ring seal 154 so that it extends into the chamber 156 where it is secured with a movable piston 158. The piston 158, which is continuously biased to the left as in Figure 2 by a spring 160, is provided with a calibrated orifice 162 which extends through the washers 164 and 166 and the plunger cup 168. The orifice 162 and construction of the plunger cup 168 will permit the plunger 152 to be moved rapidly against the force of spring 160 to the right as shown in Figure 2 when the fluid within chamber 156 passes around the periphery of the plunger cup 168. When the plunger 158 is moved to the left by spring 160, its rate of travel will be retarded as the plunger cup 168 forms a seal with the inner walls of member 143 and the flow of fluid around the plunger is prevented. The orifice 162 will restrict the flow of fluid therethrough so a considerable lapse of time will occur before the plunger 152 and piston 158 moves from right to left. The plunger 26 is normally urged to the left as in Figure 3 by a spring 170.

From the above description of parts and the following description of the operation of the various parts of the switch, it will be apparent that the dashpot 36 will supply a predetermined time delay before the button 172 on the end of plunger 26 may be redepressed after the initial depressing pressure has been removed.

When the switch is in the position as shown in Figures 24, all of the moving parts of the switch will be at rest in the furthest left position and the lug 124 and the lug will cause members 30 and 32, respectively, to be biased downwardly. When the switch is moved to the position shown in Figures 5 and 6, the carriage 28, the member 34 along with plunger 152 and the parts of the dashpot 36 will be moved slightly to the left. When the switch is in this position, the lug 124 will no longer be in contact with member 20 as it will extend partially through opening 92. This will permit the member 30 to be moved upwardly so lug 126 engages the surface portion of member 34 adjacent the inclined lug 122. When the movement of plunger 26 to the right is continued so that the parts of the switch are in the position as shown in Figure 7, the. carriage 28 will contact member 70 and through lug 114, will continue to move member 34 to the right to cause the lugs 120 on member 34 to pass from their engaging position with member 32. When lugs 120 no longer engage the member 32, the member 32 will be biased upwardly by spring 132 so that lug 136 enters opening 96 and engages the bottom surface of member 28. Also, when the switch button 172 has been moved to the position shown in Figure 7, lug 126 will have passed over the inclined surface of lug 122 to prevent movement of the member 34 to the left. It is to be noted that when the switch parts are in the position indicated in Figure 7, the carriage 28 will have moved member 70 so the toggle, as shown in Figure 8, will have caused the contacts 48 and 52 to be on the verge of closing. When the switch parts are moved a small distance from that shown in Figure 7 to that shown in Figure 9, the contacts 48 and 52, shown in Figure 10, will be in the closed position and the parts of the switch will be moved completely to the right. The lug 122 will then be to the right of lug 126 while the lug 136 will be in engagement with the bottom surface of carriage 28.

When the applied pressure on button 172 is released; the spring 170 will cause the plunger 26 and carriage 28 to begin movement to the left. When this movement occurs as shown in Figure 11, the complete movement of member 28 to the left will be prevented when lug 136 extends through opening 96 and into opening 90. At this instance, the movement of member 34 will be pre* vented by lug 126 which is engaged behind lug 122.

Further, it is apparent that, because of the relative size of carriage 28 and member 70, a lost motion action will occur therebetween and the carriage 28 may be moved without disturbing the position of member 70. Thus, when member 70 and the carriage 28 are in the position as in Figure 11, contacts 48 and 52, as shown in Figure 12, will be on the verge of opening. It will be observed in Figure 11 that the opening 90 is sized to provide a limited movement between carriage 28 and lug 136. This limited movement will permit the carriage 28 to move member 70 to the left sufliciently to cause contacts 48 and 52 to open. Once these contacts 48 and 52 are open, they will not be reclosed if the carriage 28 is moved to the right for the size of opening 90 will not permit suflicient movement of the carriage 28 to actuate toggle mechanism to a point which will cause the contacts to close. The movement of carriage 28 will also cause the wall portion of member 28, which surrounds slot 86, to ride upon the inclined surface of lug 124 and cause member 30 to be slightly moved downwardly. When member 30 moves downward, lug 126 will release member 34 and permit the action of the dashpot 36 to control the further movement to the left of member 34.

As heretofore stated, the movement of the plunger 152 and member 34 is retarded as determined by the size of orifice 162. When the member 34 moves to the left, the lugs 120 will move across the inclined surface 134 to cause member 32 to be moved downwardly and move lug 136 out of opening 90. This will permit the parts of the switch to move to the left to the position shown in Figure 3 wherefrom they may be actuated in the sequence as indicated above.

In the embodiment as shown in Figures 13-17, the plunger 200, the toggle acting contact actuator 202, which is carried by member 38 as in Figure 1, and the function of the carriage member 204 is basically the same as that described in the preceding embodiment. The difference between the embodiment as disclosed in Figure 1 and that shown in Figures 13-17 resides in the operation and construction of the lockout and delay mechanism as will be hereinafter described. In this embodiment, the carriage 204 is provided with apertures 206, 208 and 210 as shown in the drawing. The fluid dashpot 212 has a function similar to that described in the preceding embodiment and incorporates a sized orifice 214 which will control the flow of fluid within the dashpot to permit relatively free movement of lever 216 in one direction and to restrict or delay its movement in the opposite direction. The fluid dashpot 212 is carried by a support 218 which is suitably secured to the support member 220. The lever 216 is pivoted on a pin 222 carried by arm 224 which is also mounted on support 220. The pin 222 provides a common pivot for lever 216 and a lockout arm 226 which is urged upwardly by a spring 228 and downwardly by an eXtendng portion 230 of lever 216. The lever 226 is sized, when it is in its upward position, to pass through the openings 232 and 234 in support members 218 and 220, respectively, so that it may be received in opening 206 where it will limit the movement of carriage 204.

From the arrangement of parts, it is apparent that as carriage 204 is moved to the right from the position shown in Figure 16 to the position shown in Figure 17, the portion of the carriage which surrounds opening 210 will ride upon the lever 216 and cause the piston of the fluid dashpot to be moved downwardly. When the parts of the switch are inthe position shown in Figure 17, the lever 216 will be held in its downwardly depressed position by a locking means 236 which consistsof a U-shaped piece, most clearly shown in Figure 15, which has one end carried by a support 220 and the other end adapted to be received in a depression 238 in lever 216. This loclc'ing means will be held in the engaging position by a metal strip 240 which has one end secured to the carriage 204. This locking means will be released by a member 242 which is L-shaped as shown in Figures 16 and 17 and is provided with an enlarged end 244 which will engage the material of the carriage 204 which surrounds opening 210 so that a slidable, lost motion connection is provided between member 242 and carriage 204. When the parts of the switch are in the position shown in Figure 17, the contacts will be closed. From the arrangement of parts shown, it is apparent that as the carriage 204 is moved to the left, the parts of the toggle acting mechanism will not be immediately disturbed and the lever 226 will be cocked so that it will be received in opening 206 at substantially the same instance that the carriage engages the toggle acting mechanism to release the contacts. Opening 206 is elongated sufficiently so that the contacts will not be reengaged once the lever 226 has been received therein in the event that the plunger 200 is redepressed. After the lever 226 is received in opening 206 and the movement of the carriage 204 to the left is continued, the lug 244 of member 242 will cause the locking means 236 to be moved out of the detents 238 of lever 216. This will permit the force of the spring in the dashpot to move the lever 216, which, in turn, moves lever 226 from opening 206 in carriage 204. The movement of lever 216 will be delayed by the dashpot 212 so a considerable time delay will occur before the plunger 200 may be redepressed to cause the engagement of the contacts as set forth in the preceding embodiment.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An electric switch, comprising; a support member having a pair of spaced anns extending from a base,

a toggle actuated contact member carried by said arms,

a reciprocating contact actuator movable on the base between the arms of said support member arranged for actuating the toggle of said contact member, a slide member engaging said contact actuator having a portion extending through an elongated slot in said base, having a limited movement between said arms, a fluid dashpot carried by said support and connected with said member, said dashpot being adapted to permit free movement of said member in one direction and control the movement thereof in the opposite direction, a reciprocal plunger carried by said support member operably connected with said contact actuator, and locking means engageable with said slide member carried by said support member for preventing movement of said fluid controlled member when said contact actuator is in a predetermined position relative to said arms.

2. In an electric switch, the combination comprising; a base member having an aperture, a snap acting toggle controlled switch supported by said base and including a fixed contact and a movable toggle controlled contact, a carriage slidably supported by said base member and movable relative thereto, said carriage having a latch receiving aperture and including means for actuating said movable contact to a closed position in one direction of movement and for returning said movable contact to an open position during movement in an opposite direction, an actuator member connected to said carriage, a spring connected between said base member and said actuator member for biasing said carriage member toward a position wherein said switch is in an open position, said latch 7 receiving aperture being in alignment with said aperture in said base member in one position of said carriage, a slide member slidably supported by said base member having a portion engageable with said carriage whereby sa1d carr1age and slide members move together when said carnage is being operated to close said switch, a fluid dashpot having a movable part engaging said slide member, said movable part having substantially unrestrained movement in one direction of movement corresponding to switch closing movement of said carriage and having a retarded movement in an opposite direction correspondmg to switch opening movement of said carriage, a second spring biasing said movable part in its retarded direction of movement, a first latch bar pivotally supported by said base and spring biased toward said base, a second latch bar pivotally supported by said base and sprlng biased toward said base, said second latch bar having a portion that swings into the aperture formed in said base and which swings into the latch receiving aperture of said carriage when said apertures are aligned, shoulder means on said slide member engageable with said first latch bar when said carriage is moved to circuit closing position, cam means on said slide engageable with said second locking bar for preventing entry of said portion of said bar into said latch receiving aperture when said carriage is being moved to a switch closing position, said shoulder means engaging said slide member when said carriage is moving toward a switch opening position whereby said carriage and slide member move relative to each other to align said apertures and said portion of said second latching bar swings into said latch receiving aperture to prevent further movement of said carriage, said cam means subsequently releasing said second latching bar by movement of said slide member toward switch opening position.

3. In an electric switch, the combination comprising; a base member having a first aperture, a movable contact member, a fixed contact member adapted to be engaged by said movable contact member when said switch is in a closed position, a reciprocable carriage member slidable with respect to said base including means for operating said movable contact member, said carriage member having a first position wherein said switch is open and having a second position wherein said switch is closed, means for operating said carriage member from said first position to said second position, first resilient means constantly biasing said carriage member toward said first position, a slide member slidable with respect to said base having a portion engaging said carriage member whereby said slide member is moved with said carriage member when said carriage member is moved toward said second position, said carriage member moving independently of said slide member when said carriage member is moved toward said first position, second resilient means biasing said slide member into engagement with said carriage member and biasing said carriage member toward said first position when said carriage member and slide member are moving together toward said second position, a second aperture in said carriage member which is in alignment with said first aperture in one position of said carriage member, a movable latch member supported by said base having a tongue portion that is adapted to swing into both of said apertures when they are aligned with each other to lock said carriage member from movement, resilient means biasing said latch'mernber to a latching position, means on said slide member for preventing entry of said tongue portion into the aperture formed in said carriage member when said carriage member and said slide member are being moved together from said first position toward said second position and means causing relative movement between said carriage member and said slide member when said carriage member and slide member are moving from said second position toward said first position under the influence of said second resilient means whereby said means on said slide member is ineffective to prevent entry of said tongue member into said apertures when they become aligned, said means on said slide member upon continued movement thereof toward said first position releasing said carriage member for movement toward said first or second position.

4. In an electric switch, the combination comprising; an electric switch mechanism including a movable contact adapted to engage another contact in its closed position, a movable actuating member having first and second positions, said actuating member moving said switch from an open to a closed position when it is moved from said first to said second position and moving said switch from a closed to an open position when it is moved from said second to said first position, means biasing said actuating member toward said first position, manually operable means for moving said actuating member from said first to said second position against the force of said biasing means, latching means engageable with said actuating member for locking said actuating member from movement when said actuating member is in a position intermediate said first and second positions, means preventing engagement of said latching means with said actuating member when said actuating member is initially moved from said first position to said second position to close said switch, means permitting engagement of said latching means with said actuating member when said actuating member is being moved from said second position to said first position and when it reaches said intermediate position, and means for releasing said latching means whereby said actuating member moves to said first position under the influence of said biasing means.

5. In an electric switch, the combination comprising; an electrical switch device having a movable contact that is engageable with another contact when the switch is in a closed position, a movable actuating member having first and second positions, said actuating member moving said switch from an open to a closed position when it is moved from said first to said second position and moving said switch from a closed to an open position when it is moved from said second to said first position, means for operating said actuating member, means biasing said actuating member toward said first position, a slide member operated by said actuating member when said actuating member is moved from said first to said second position, a retarding device having a movable part engaging said slide member, said retarding device providing for a substantially unrestrained movement of said movable part when said actuating member is moved from said first to said second position and applying a retarded force to said slide member when said actuating member is being moved toward said first position, latch means engageable with said actuating member when said actuating member is in a position intermediate said first and second position, means preventing engagement of said latch means with said actuating member when said actuating member is moving from said first to said second position to close said switch, means permitting engagement of said latching means with said actuating member when said actuating member is being moved from said second position to said first position and when it reaches said intermediate position, and means for releasing said latching means in response to movement of said slide member by said retarding device toward said first position.

6. In an electric switch, the combination comprising; an electric switch device having a movable contact that is engageable with another contact when the switch is in a closed position, a movable actuating member for closing and opening said switch, said actuating member having first and second positions, an operating member for moving said actuating member, first resilient means for biasing said actuating member toward said first position, a movable slide member having a portion engageable with said actuating member, second resilient means biasing said slide member into engagement with said actuating member, said first and second resilient means both being compressed when said actuating member and slide member are moved from said first to said second position, fluid dashpot means operating on said second resilient means providing substantially unstrained movement of said resilient means when it is being compressed and retarding movement of said second resilient means when said resilient means is applying a force to said slide member to move said slide member and actuating member toward said first position whereby said actuating member moves relative to said slide member when said members are moving toward said first position, latching means engageable with said actuating member for preventing movement thereof when said actuating member is in a position intermediate said first and second position, means preventing engagement of said latching means with said actuating member when said actuating member and slide member are moving together and toward said second position, means responsive to relative movement of said actuating member and slide member when said members are being moved toward said first position for permitting engagement of said latching means with said actuating member, and means responsive to continued movement of said slide member by said second resilient means toward said first position for releasing said latching means.

7. In an electric switch, the combination comprising; a movable contact reciprocating means for moving the movable contact of said switch, said reciprocating means being movable between first and second positions, reciprocal restraining means freely movable with the reciprocating means when the reciprocating means is mov- 30 2,543,090

ing toward said second position and having a restrained movement in the opposite direction, locking means for preventing movement of said reciprocating means when said reciprocating means is in a position intermediate said 35 first and second positions, means for preventing locking of said reciprocating means by said locking means when said reciprocating means is initially moved from said first to said second position, and means permitting locking of said reciprocating means by said locking means when said reciprocating means is thereafter moved from said second to said first position.

8. In an electric switch, the combination comprising; electric switch mechanism including a movable contact that engages another contact when the switch is in a closed position, a movable switch actuator having first and second positions, said switch actuator operating to close said switch when it is moved from said first to said second position and to open said switch when it is moved from said second to said first position, locking means for at times preventing movement of said switch actuator when said switch actuator is in a position intermediate said first and second positions, means for preventing locking of said switch actuator by said locking means when said switch actuator is initially moved from said first to said second position and across said intermediate position, and means permitting locking of said switch actuator by said locking means when said switch actuator is thereafter moved from said second to said first position and at said intermediate position.

References Cited in the file of this patent UNITED STATES PATENTS 2,148,472 Joy Feb. 28, 1939 Ballou Feb. 27, 1951 2,670,413 Shockley Feb. 23, 1954 FOREIGN PATENTS Great Britain July 21, 1954 

